In case someone is interested, for new parts that are e-coated you should red scotchbright them to provide a rough surface for the paint to stick on. For parts that are already painted your goal should be to get most of the clearcoat out with DA 320 grit or 400 grit handsanding. You want to make sure that the basecoat is still in good shape so that you are painting on a good and adhesive surface. Be sure to get any rust off and feather the edges of the rust spots from bare metal to primer to basecoat with each layer being at least 1/4." This will help when you are painting. Hope it helps someone.
I would also recommend test fitting all your parts before prepping them for paint. This way you know how everything fits and you can verify that things are right before you paint them. You want to have the confidence that you can bolt things back together with little massaging once it painted.